Liquid crystal composition and liquid crystal display device

ABSTRACT

To provide a liquid crystal composition satisfying at least one of characteristics such as high maximum temperature, low minimum temperature, small viscosity, suitable optical anisotropy, large negative dielectric anisotropy, large specific resistance, high stability to ultraviolet light and heat, or having a suitable balance regarding at least two of the characteristics; and an AM device having characteristics such as short response time, a large voltage holding ratio, low threshold voltage, a large contrast ratio and long service life. The composition has negative dielectric anisotropy and contains a specific compound having large negative dielectric anisotropy as a first component, a specific compound having small viscosity as a second component, and may contain a specific compound having high maximum temperature or small viscosity as a third component, a specific compound having negative dielectric anisotropy as a fourth component, or a specific compound having a polymerizable group as an additive component.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Japan Patent Application no. 2014-196326, filed on Sep. 26, 2014. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

TECHNICAL FIELD

The invention relates to a liquid crystal composition, a liquid crystal display device including the composition and so forth. In particular, the invention relates to a liquid crystal composition having a negative dielectric anisotropy, and a liquid crystal display device that includes the composition and has a mode such as an IPS mode, a VA mode, an FFS mode and an FPA mode. The invention also relates to a liquid crystal display device having a polymer sustained alignment mode.

BACKGROUND ART

In a liquid crystal display device, a classification based on an operating mode for liquid crystal molecules includes a phase change (PC) mode, a twisted nematic (TN) mode, a super twisted nematic (STN) mode, an electrically controlled birefringence (ECB) mode, an optically compensated bend (OCB) mode, an in-plane switching (IPS) mode, a vertical alignment (VA) mode, a fringe field switching (FFS) mode and a field-induced photo-reactive alignment (FPA) mode. A classification based on a driving mode in the device includes a passive matrix (PM) and an active matrix (AM). The PM is classified into static, multiplex and so forth, and the AM is classified into a thin film transistor (TFT), a metal insulator metal (MIM) and so forth. The TFT is further classified into amorphous silicon and polycrystal silicon. The latter is classified into a high temperature type and a low temperature type according to a production process. A classification based on a light source includes a reflective type utilizing natural light, a transmissive type utilizing backlight and a transflective type utilizing both the natural light and the backlight.

A liquid crystal display device includes a liquid crystal composition having a nematic phase. The composition has suitable characteristics. An AM device having good characteristics can be obtained by improving the characteristics of the composition. Table 1 below summarizes a relationship of the characteristics between two aspects. The characteristics of the composition will be further described based on a commercially available AM device. A temperature range of the nematic phase relates to a temperature range in which the device can be used. A preferred maximum temperature of the nematic phase is approximately 70° C. or higher and a preferred minimum temperature of the nematic phase is approximately −10° C. or lower. Viscosity of the composition relates to a response time in the device. A short response time is preferred for displaying moving images on the device. A shorter response time even by one millisecond is desirable. Accordingly, a small viscosity in the composition is preferred. A small viscosity at a low temperature is further preferred.

TABLE 1 Characteristics of Composition and AM Device No. Characteristics of Composition Characteristics of AM Device 1 Wide temperature range of a Wide usable temperature range nematic phase 2 Small viscosity Short response time 3 Suitable optical anisotropy Large contrast ratio 4 Large positive or negative Low threshold voltage and small dielectric anisotropy electric power consumption Large contrast ratio 5 Large specific resistance Large voltage holding ratio and large contrast ratio 6 High stability to ultraviolet Long service life light and heat

An optical anisotropy of the composition relates to a contrast ratio in the device. According to the mode of the device, a large optical anisotropy or a small optical anisotropy, namely, a suitable anisotropy is required. A product (Δn×d) of the optical anisotropy (Δn) of the composition and a cell gap (d) in the device is designed so as to maximize the contrast ratio. A suitable value of the product depends on a type of the operating mode. In a device having the VA mode, the suitable value is in the range of approximately 0.30 micrometer to approximately 0.40 micrometer, and in a device having the IPS mode or the FFS mode, the suitable value is in the range of approximately 0.20 micrometer to approximately 0.30 micrometer. In the above cases, a composition having a large optical anisotropy is preferred for a device having a small cell gap. A large value of dielectric anisotropy in the composition contributes to a low threshold voltage, a small electric power consumption and a large contrast ratio in the device. Accordingly, the large value of dielectric anisotropy is preferred. A large specific resistance in the composition contributes to a large voltage holding ratio and a large contrast ratio in the device. Accordingly, a composition having a large specific resistance at room temperature and also at a temperature close to the maximum temperature of the nematic phase in an initial stage is preferred. A composition having a large specific resistance at room temperature and also at a temperature close to the maximum temperature of the nematic phase even after the device has been used for a long period of time is preferred. Stability of the composition to ultraviolet light and heat relates to a service life of the device. In the case where the stability is high, the device has a long service life. Such characteristics are preferred for an AM device for use in a liquid crystal projector, a liquid crystal television and so forth.

A liquid crystal composition containing a polymer is used for a liquid crystal display device having a polymer sustained alignment (PSA) mode. First, a composition to which a small amount of polymerizable compound is added is injected into the device. Next, the composition is irradiated with ultraviolet light while voltage is applied between substrates of the device. The polymerizable compound is polymerized to form a network structure of the polymer in the composition. In the composition, alignment of liquid crystal molecules can be controlled by the polymer, and therefore a response time of the device is shortened and image persistence is improved. Such an effect of the polymer can be expected for a device having a mode such as the TN mode, the ECB mode, the OCB mode, the IPS mode, the VA mode, the FFS mode and the FPA mode.

A composition having a positive dielectric anisotropy is used for an AM device having the TN mode. A composition having a negative dielectric anisotropy is used for an AM device having the VA mode. A composition having a positive or negative dielectric anisotropy is used for an AM device having the IPS mode or the FFS mode. A composition having a positive or negative dielectric anisotropy is used for an AM device having the polymer sustained alignment mode. Examples of the liquid crystal composition having the negative dielectric anisotropy are disclosed in Patent literature Nos. 1 to 6 as described below.

CITATION LIST Patent Literature

Patent literature No. 1: JP H11-152474 A.

Patent literature No. 2: JP 2000-053602 A.

Patent literature No. 3: JP 2003-327965 A.

Patent literature No. 4: JP 2003-517494 A.

Patent literature No. 5: JP H2-501071 A.

Patent literature No. 6: JP H2-503568 A.

SUMMARY OF INVENTION

The invention concerns a liquid crystal composition that has a negative dielectric anisotropy and contains at least one compound selected from the group of compounds represented by formula (1) as a first component, and at least one compound represented by formula (2) as a second component, and a liquid crystal display device including the composition:

wherein, in formula (1), R¹ and R² are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxy having 2 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine; Z¹ and Z² are independently a single bond, ethylene, carbonyloxy or methyleneoxy; and X¹, X², X³ and X⁴ are independently hydrogen, fluorine or chlorine, wherein, at least one of X¹, X², X³ and X⁴ is fluorine or chlorine.

The invention also concerns use of the liquid crystal composition in a liquid crystal display device.

The invention further concerns use of the liquid crystal composition in a polymer sustained alignment mode liquid crystal display device.

DESCRIPTION OF EMBODIMENTS

Usage of terms herein is as described below. A term “liquid crystal composition” and “liquid crystal display device” may be occasionally abbreviated as “composition” and “device,” respectively. “Liquid crystal display device” is a generic term for a liquid crystal display panel and a liquid crystal display module. “Liquid crystal compound” is a generic term for a compound having a liquid crystal phase such as a nematic phase and a smectic phase, and a compound having no liquid crystal phase but being mixed with the composition for the purpose of adjusting characteristics such as a temperature range of the nematic phase, viscosity and dielectric anisotropy. The compound has a six-membered ring, such as 1,4-cyclohexylene and 1,4-phenylene, and has rod like molecular structure. “Polymerizable compound” includes a compound to be added to the composition for the purpose of forming a polymer in the composition.

The liquid crystal composition is prepared by mixing a plurality of liquid crystal compounds. A ratio (content) of the liquid crystal compounds is expressed in terms of weight percent (% by weight) based on the weight of the liquid crystal composition. An additive such as an optically active compound, an antioxidant, an ultraviolet light absorber, a dye, an antifoaming agent, a polymerizable compound, a polymerization initiator and a polymerization inhibitor is added to the liquid crystal composition, when necessary. A ratio (amount of addition) of the additive is expressed in terms of weight percent (% by weight) based on the weight of the liquid crystal composition in a manner similar to the ratio of the liquid crystal compounds. Weight parts per million (ppm) may be occasionally used. A ratio of the polymerization initiator and the polymerization inhibitor is exceptionally expressed based on the weight of the polymerizable compound.

“Higher limit of a temperature range of the nematic phase” may be occasionally abbreviated as “maximum temperature.” “Lower limit of the temperature range of the nematic phase” may be occasionally abbreviated as “minimum temperature.” An expression “having a large specific resistance” means that the composition has a large specific resistance at room temperature and also at a temperature close to the maximum temperature of the nematic phase in an initial stage, and that the composition has a large specific resistance at room temperature and also at a temperature close to the maximum temperature of the nematic phase even after the device has been used for a long period of time. An expression “having a large voltage holding ratio” means that the device has a large voltage holding ratio at room temperature and also at a temperature close to the maximum temperature of the nematic phase in an initial stage, and that the device has a large voltage holding ratio at room temperature and also at a temperature close to the maximum temperature of the nematic phase even after the device has been used for a long period of time. An expression “to increase the dielectric anisotropy” means that a value thereof positively increases for the composition having a positive dielectric anisotropy, and that the value negatively increases for the composition having a negative dielectric anisotropy.

A compound represented by formula (1) may be occasionally abbreviated as “compound (1).” At least one compound selected from the group of compounds represented by formula (3) may be occasionally abbreviated as “compound (3).” A term “compound (3)” means that the compound represented by formula (3) includes one compound, a mixture of two compounds, or a mixture of three or more compounds. A same rule applies also to any other compound represented by any other formula. An expression “at least one of ‘A’” means that the number of ‘A’ is arbitrary. An expression “at least one of ‘A’ may be replaced by ‘B’” means that, when the number of ‘A’ is 1, a position of ‘A’ is arbitrary, and when the number of ‘A’ is 2 or more, positions thereof can be selected without limitation. A same rule applies also to an expression “at least one of ‘A’ is replaced by ‘B’.”

A symbol of terminal group R¹ is used for a plurality of compounds in chemical formulas of component compounds. In the compounds, two groups represented by two of arbitrary R¹ may be identical or different. In one case, for example, R¹ of compound (1-1) is ethyl and R¹ of compound (1-2) is ethyl. In another case, R¹ of compound (1-1) is ethyl and R¹ of compound (1-2) is propyl. A same rule applies also to a symbol of any other terminal group or the like. In formula (3), when n is 2, two of ring A exist. In the compound, two rings represented by two of ring A may be identical or different. A same rule applies also to two of arbitrary ring A when n is larger than 2. A same rule applies also to a symbol such as Z³ and ring C. A same rule applies also to such a case where two of -Sp²-P⁵ exists in compound (5-27).

Symbols A, B, C or the like surrounded by a hexagonal shape correspond to six-membered rings such as ring A, ring B and ring C, respectively. In compound (5), a hexagonal shape represents a six-membered ring or a condensed ring. An oblique line crossing the hexagonal shape indicates that arbitrary hydrogen on the ring can be replaced by -Sp¹-P¹ group or the like. A subscript such as h represents the number of groups to be replaced. When the subscript is 0, no such replacement exists. When h is 2 or more, a plurality of -Sp¹-P¹ exist on ring K. The plurality of groups represented by -Sp¹-P¹ may be identical or different.

Then, 2-fluoro-1,4-phenylene means two divalent groups described below. In a chemical formula, fluorine may be leftward (L) or rightward (R). A same rule applies also to an asymmetrical divalent group derived from a ring, such as tetrahydropyran-2,5-diyl. A same rule applies also to a divalent bonding group such as carbonyloxy (—COO or —OCO—).

The invention includes items described below.

Item 1. A liquid crystal composition that has a negative dielectric anisotropy, and contains at least one compound selected from the group of compounds represented by formula (1) as a first component, and at least one compound represented by formula (2) as a second component:

wherein, in formula (1), R¹ and R² are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxy having 2 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine; Z¹ and Z² are independently a single bond, ethylene, carbonyloxy or methyleneoxy; and X¹, X², X³ and X⁴ are independently hydrogen, fluorine or chlorine, wherein, at least one of X¹, X², X³ and X⁴ is fluorine or chlorine.

Item 2. The liquid crystal composition according to item 1, containing at least one compound selected from the group of compounds represented by formulas (1-1) to (1-3) as the first component:

wherein, in formulas (1-1) to (1-3), R¹ and R² are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxy having 2 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine.

Item 3. The liquid crystal composition according to item 1 or 2, wherein a ratio of the first component is in the range of 5% by weight to 30% by weight, and a ratio of the second component is in the range of 5% by weight to 40% by weight, based on the weight of the liquid crystal composition.

Item 4. The liquid crystal composition according to anyone of items 1 to 3, containing at least one compound selected from the group of compounds represented by formula (3) as a third component:

wherein, in formula (3), R³ and R⁴ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine, or alkenyl having 2 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine; ring A and ring B are independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene or 2,5-difluoro-1,4-phenylene; Z³ is a single bond, ethylene or carbonyloxy; n is 1, 2 or 3; wherein, when n is 1, ring B is 1,4-phenylene.

Item 5. The liquid crystal composition according to any one of items 1 to 4, containing at least one compound selected from the group of compounds represented by formulas (3-1) to (3-12) as the third component:

wherein, in formulas (3-1) to (3-12), R³ and R⁴ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine, or alkenyl having 2 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine.

Item 6. The liquid crystal composition according to item 4 or 5, wherein a ratio of the third component is in the range of 5% by weight to 50% by weight based on the weight of the liquid crystal composition.

Item 7. The liquid crystal composition according to anyone of items 1 to 6, containing at least one compound selected from the group of compounds represented by formula (4) as a fourth component:

wherein, in formula (4), R⁵ and R⁶ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxy having 2 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine; ring C and ring E are independently 1,4-cyclohexylene, 1,4-cyclohexenylene, tetrahydropyran-2,5-diyl, 1,4-phenylene, or 1,4-phenylene in which at least one of hydrogen is replaced by fluorine or chlorine; ring D is 2,3-difluoro-1,4-phenylene, 2-chloro-3-fluoro-1,4-phenylene, 2,3-difluoro-5-methyl-1,4-phenylene, 3,4,5-trifluoronaphthalene-2,6-diyl or 7,8-difluorochroman-2,6-diyl; Z⁴ and Z⁵ are independently a single bond, ethylene, carbonyloxy or methyleneoxy; p is 1, 2 or 3; q is 0 or 1; a sum of p and q is 3 or less; wherein, when p is 2 and q is 0, at least one of ring C is 1,4-cyclohexylene, 1,4-cyclohexenylene or tetrahydropyran-2,5-diyl.

Item 8. The liquid crystal composition according to anyone of items 1 to 7, containing at least one compound selected from the group of compounds represented by formulas (4-1) to (4-19) as the fourth component:

wherein, in formulas (4-1) to (4-19), R⁵ and R⁶ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxy having 2 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine.

Item 9. The liquid crystal composition according to item 7 or 8, wherein a ratio of the fourth component is in the range of 10% by weight to 80% by weight based on the weight of the liquid crystal composition.

Item 10. The liquid crystal composition according to anyone of items 1 to 9, containing at least one polymerizable compound selected from the group of compounds represented by formula (5) as an additive component:

wherein, in formula (5), ring K and ring M are independently cyclohexyl, cyclohexenyl, phenyl, 1-naphthyl, 2-naphthyl, tetrahydropyran-2-yl, 1,3-dioxane-2-yl, pyrimidine-2-yl or pyridine-2-yl, and in the rings, at least one of hydrogen may be replaced by fluorine, chlorine, alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine; ring L is 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, naphthalene-1,2-diyl, naphthalene-1,3-diyl, naphthalene-1,4-diyl, naphthalene-1,5-diyl, naphthalene-1,6-diyl, naphthalene-1,7-diyl, naphthalene-1,8-diyl, naphthalene-2,3-diyl, naphthalene-2,6-diyl, naphthalene-2,7-diyl, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, pyrimidine-2,5-diyl or pyridine-2,5-diyl, and in the rings, at least one of hydrogen may be replaced by fluorine, chlorine, alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine; Z⁶ and Z⁷ are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one of —CH₂— may be replaced by —O—, —CO—, —COO— or —OCO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH—, —C(CH₃)═CH—, —CH═C(CH₃)— or —C(CH₃)═C(CH₃)—, and in the groups, at least one of hydrogen may be replaced by fluorine or chlorine; P¹, P² and P³ are independently a polymerizable group; Sp¹, Sp² and Sp³ are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one of —CH₂— may be replaced by —O—, —COO—, —OCO— or —OCOO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH— or —C≡C—, and in the groups, at least one of hydrogen may be replaced by fluorine or chlorine; g is 0, 1 or 2; h, j and k are independently 0, 1, 2, 3 or 4; and a sum of h, j and k is 1 or more.

Item 11. The liquid crystal composition according to item 10, wherein, in formula (5), P¹, P² and P³ are independently a polymerizable group selected from the group of groups represented by formulas (P-1) to (P-5):

wherein, in formulas (P-1) to (P-5), M¹, M² and M³ are independently hydrogen, fluorine, alkyl having 1 to 5 carbons, or alkyl having 1 to 5 carbons in which at least one of hydrogen is replaced by fluorine or chlorine.

Item 12. The liquid crystal composition according to any one of items 1 to 11, containing at least one polymerizable compound selected from the group of compounds represented by formulas (5-1) to (5-27) as the additive component:

wherein, in formulas (5-1) to (5-27), P⁴, P⁵ and P⁶ are independently a polymerizable group selected from the group of groups represented by formulas (P-1) to (P-3):

wherein, in formulas (P-1) to (P-3), M¹, M² and M³ are independently hydrogen, fluorine, alkyl having 1 to 5 carbons, or alkyl having 1 to 5 carbons in which at least one of hydrogen is replaced by fluorine or chlorine; in formulas (5-1) to (5-27), Sp¹, Sp² and Sp³ are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one of —CH₂— may be replaced by —O—, —COO—, —OCO— or —OCOO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH— or —C≡C—, and in the groups, at least one of hydrogen may be replaced by fluorine or chlorine.

Item 13. The liquid crystal composition according to any one of items 10 to 12, wherein a ratio of addition of the additive component is in the range of 0.03% by weight to 10% by weight based on the weight of the liquid crystal composition.

Item 14. A liquid crystal display device, including the liquid crystal composition according to any one of items 1 to 13.

Item 15. The liquid crystal display device according to item 14, wherein an operating mode in the liquid crystal display device is an IPS mode, a VA mode, an FFS mode or an FPA mode, and a driving mode in the liquid crystal display device is an active matrix mode.

Item 16. A polymer sustained alignment mode liquid crystal display device, wherein the liquid crystal display device includes the liquid crystal composition according to any one of items 10 to 13, or the polymerizable compound in the liquid crystal composition is polymerized.

Item 17. Use of the liquid crystal composition according to any one of items 1 to 13 in a liquid crystal display device.

Item 18. Use of the liquid crystal composition according to any one of items 10 to 13 in a polymer sustained alignment mode liquid crystal display device.

The invention further includes the following items: (a) the composition, further containing at least one additive such as the optically active compound, the antioxidant, the ultraviolet light absorber, the dye, the antifoaming agent, the polymerizable compound, the polymerization initiator and the polymerization inhibitor; (b) an AM device including the composition; (c) a polymer sustained alignment (PSA) mode AM device including the composition further containing the polymerizable compound; (d) a polymer sustained alignment (PSA) mode AM device including the composition in which the polymerizable compound in the composition is polymerized; (e) a device including the composition and having the PC mode, the TN mode, the STN mode, the ECB mode, the OCB mode, the IPS mode, the VA mode, the FFS mode or the FPA mode; (f) a transmissive device including the composition; (g) use of the composition as the composition having the nematic phase; (h) use as an optically active composition by adding the optically active compound to the composition.

The composition of the invention will be described in the following order. First, a constitution of the component compounds in the composition will be described. Second, main characteristics of the component compounds and main effects of the compounds on the composition will be described. Third, a combination of components in the composition, a preferred ratio of the components and the basis thereof will be described. Fourth, a preferred embodiment of the component compounds will be described. Fifth, a preferred component compound will be shown. Sixth, an additive that may be added to the composition will be described. Seventh, methods for synthesizing the component compounds will be described. Last, an application of the composition will be described.

First, the constitution of the component compounds in the composition will be described. The composition of the invention is classified into composition A and composition B. Composition A may further contain any other liquid crystal compound, additive or the like in addition to the liquid crystal compound selected from compound (1), compound (2), compound (3) and compound (4). “Any other liquid crystal compound” means a liquid crystal compound different from compound (1), compound (2), compound (3) and compound (4). Such a compound is mixed with the composition for the purpose of further adjusting the characteristics. The additive includes the optically active compound, the antioxidant, the ultraviolet light absorber, the dye, the antifoaming agent, the polymerizable compound, the polymerization initiator and the polymerization inhibitor.

Composition B consists essentially of the liquid crystal compound selected from compound (1), compound (2), compound (3) and compound (4). A term “essentially” means that the composition may contain the additive, but does not contain any other liquid crystal compound. Composition B has a smaller number of components than composition A has. Composition B is preferred to composition A in view of cost reduction. Composition A is preferred to composition B in view of possibility of further adjusting the characteristics by mixing any other liquid crystal compound.

Second, the main characteristics of the component compounds and the main effects of the compounds on the characteristics of the composition will be described. The main characteristics of the component compounds are summarized in Table 2 on the basis of advantageous effects of the invention. In Table 2, a symbol L stands for “large” or “high,” a symbol M stands for “medium,” and a symbol S stands for “small” or “low.” The symbols L, M and S represent a classification based on a qualitative comparison among the component compounds, and 0 (zero) means that a value is zero or nearly zero.”

TABLE 2 Characteristics of Compounds Compounds Compound Compound Compound Compound (1) (2) (3) (4) Maximum S to M M S to L S to L temperature Viscosity L S S to M M to L Optical M to L S S to L M to L anisotropy Dielectric L¹⁾ 0 0 M to L¹⁾ anisotropy Specific L L L L resistance ¹⁾Compounds having a negative dielectric anisotropy value.

Upon mixing the component compounds with the composition, the main effects of the component compounds on the characteristics of the composition are as described below. Compound (1) increases the dielectric anisotropy. Compound (2) decreases the viscosity. Compound (3) increases the maximum temperature or decreases the viscosity. Compound (4) increases the dielectric anisotropy and decreases the minimum temperature. Compound (5) is polymerized to give a polymer, and the polymer shortens the response time in the device and improves image persistence.

Third, the combination of components in the composition, the preferred ratio of the component compounds and the basis thereof will be described. A preferred combination of components in the composition includes a combination of the first component and the second component, a combination of the first component, the second component and the third component, a combination of the first component, the second component and the fourth component, a combination of the first component, the second component and the additive component, a combination of the first component, the second component, the third component and the fourth component, a combination of the first component, the second component, the third component and the additive component, a combination of the first component, the second component, the fourth component and the additive component, or a combination of the first component, the second component, the third component, the fourth component and the additive component. A further preferred combination includes the combination of the first component, the second component, the third component and the fourth component, or the combination of the first component, the second component, the third component, the fourth component and the additive component.

A preferred ratio of the first component is approximately 5% by weight or more in order to increase the dielectric anisotropy and approximately 30% by weight or less for decreasing the minimum temperature. A further preferred ratio is in the range of approximately 5% by weight to approximately 25% by weight. A particularly preferred ratio is in the range of approximately 5% by weight to approximately 20% by weight.

A preferred ratio of the second component is approximately 5% by weight or more for decreasing the viscosity, and approximately 40% by weight or less for decreasing the minimum temperature. A further preferred ratio is in the range of approximately 5% by weight to approximately 35% by weight. A particularly preferred ratio is in the range of approximately 10% by weight to approximately 30% by weight.

A preferred ratio of the third component is approximately 5% by weight or more for increasing the maximum temperature or decreasing the viscosity, and approximately 50% by weight or less for increasing the dielectric anisotropy. A further preferred ratio is in the range of approximately 5% by weight to approximately 45% by weight. A particularly preferred ratio is in the range of approximately 5% by weight to approximately 35% by weight.

A preferred ratio of the fourth component is approximately 10% by weight or more for increasing the dielectric anisotropy, and approximately 80% by weight or less for decreasing the minimum temperature. A further preferred ratio is in the range of approximately 20% by weight to approximately 70% by weight. A particularly preferred ratio is in the range of approximately 25% by weight to approximately 65% by weight.

Compound (5) is added to the composition for the purpose of adapting the composition for the polymer sustained alignment mode device. A preferred ratio of the additive component is approximately 0.03% by weight or more in order to align the liquid crystal molecules, and approximately 10% by weight or less in order to prevent poor display in the device. A further preferred ratio is in the range of approximately 0.1% by weight to approximately 2% by weight. A particularly preferred ratio is in the range of approximately 0.2% by weight to approximately 1.0% by weight.

Fourth, the preferred embodiment of the component compounds will be described. In formula (1), formula (2), formula (3) and formula (4), R¹, R², R⁵ and R⁶ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxy having 2 to 12 carbons or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine. Preferred R¹, R², R⁵ or R⁶ is alkyl having 1 to 12 carbons for increasing the stability, and alkoxy having 1 to 12 carbons for increasing the dielectric anisotropy. R³ and R⁴ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine, or alkenyl having 2 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine. Preferred R³ or R⁴ is alkenyl having 2 to 12 carbons for decreasing the viscosity, and alkyl having 1 to 12 carbons for increasing the stability. Alkyl is straight-chain alkyl or branched-chain alkyl, but includes no cyclic alkyl. Straight-chain alkyl is preferred to branched-chain alkyl. A same rule applies also to a terminal group such as alkoxy and alkenyl.

Preferred alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl or octyl. Further preferred alkyl is ethyl, propyl, butyl, pentyl or heptyl for decreasing the viscosity.

Preferred alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy or heptyloxy. Further preferred alkoxy is methoxy or ethoxy for decreasing the viscosity.

Preferred alkenyl is vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl or 5-hexenyl. Further preferred alkenyl is vinyl, 1-propenyl, 3-butenyl or 3-pentenyl for decreasing the viscosity. A preferred configuration of —CH═CH— in the alkenyl depends on a position of a double bond. Trans is preferred in alkenyl such as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl, 3-pentenyl and 3-hexenyl for decreasing the viscosity or the like. Cis is preferred in alkenyl such as 2-butenyl, 2-pentenyl and 2-hexenyl.

Preferred examples of alkyl in which at least one of hydrogen is replaced by fluorine or chlorine include fluoromethyl, 2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluorohexyl, 7-fluoroheptyl or 8-fluorooctyl. Further preferred examples include 2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl or 5-fluoropentyl for increasing the dielectric anisotropy.

Preferred examples of alkenyl in which at least one of hydrogen is replaced by fluorine or chlorine include 2,2-difluorovinyl, 3,3-difluoro-2-propenyl, 4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenyl or 6,6-difluoro-5-hexenyl. Further preferred examples include 2,2-difluorovinyl or 4,4-difluoro-3-butenyl for decreasing the viscosity.

Ring A and ring B are independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene or 2,5-difluoro-1,4-phenylene. Preferred ring A or ring B is 1,4-cyclohexylene for decreasing the viscosity or increasing the maximum temperature, and 1,4-phenylene for decreasing the minimum temperature. With regard to a configuration of 1,4-cyclohexylene, trans is preferred to cis for increasing the maximum temperature.

Ring C and ring E are independently 1,4-cyclohexylene, 1,4-cyclohexenylene, tetrahydropyran-2,5-diyl, 1,4-phenylene, or 1,4-phenylene in which at least one of hydrogen is replaced by fluorine or chlorine. Preferred ring C or ring E is 1,4-cyclohexylene for decreasing the viscosity, tetrahydropyran-2,5-diyl for increasing the dielectric anisotropy, and 1,4-phenylene for increasing the optical anisotropy. Tetrahydropyran-2,5-diyl includes:

and preferably,

Ring D is 2,3-difluoro-1,4-phenylene, 2-chloro-3-fluoro-1,4-phenylene, 2,3-difluoro-5-methyl-1,4-phenylene, 3,4,5-trifluoronaphthalene-2,6-diyl or 7,8-difluorochroman-2,6-diyl. Preferred ring D is 2,3-difluoro-1,4-phenylene for decreasing the viscosity, 2-chloro-3-fluoro-1,4-phenylene for decreasing the optical anisotropy, 7,8-difluorochroman-2,6-diyl for increasing the dielectric anisotropy.

Z¹, Z², Z⁴ and Z⁵ are independently a single bond, ethylene, carbonyloxy or methyleneoxy. Preferred Z¹, Z², Z⁴ or Z⁵ is a single bond for decreasing the viscosity, ethylene for decreasing the minimum temperature, and methyleneoxy for increasing the dielectric anisotropy. Z³ is a single bond, ethylene or carbonyloxy. Preferred Z³ is a single bond for increasing the stability.

X¹, X², X³ and X⁴ are independently hydrogen, fluorine or chlorine, and at least one of X¹, X², X³ and X⁴ is fluorine or chlorine. Any one of preferred X¹, X², X³ or X⁴ is fluorine or chlorine, and other three are hydrogen.

Then, n is 1, 2 or 3. Preferred n is 1 for decreasing the viscosity, and 2 or 3 for increasing the maximum temperature. Then, p is 1, 2 or 3, q is 0 or 1, and a sum of p and q is 3 or less. Preferred p is 1 for decreasing the viscosity, and 2 or 3 for increasing the maximum temperature. Preferred q is 0 for decreasing the viscosity, and 1 for decreasing the minimum temperature.

In formula (5), P¹, P² and P³ are independently a polymerizable group. Preferred P¹, P² or P³ is a polymerizable group selected from the group of groups represented by formulas (P-1) to (P-5). Further preferred P¹, P² or P³ is the group represented by formula (P-1), (P-2) or (P-3). Particularly preferred P¹, P² or P³ is the group represented by formula (P-1) or (P-2). Most preferred P¹, P², or P³ is the group represented by formula (P-1). A preferred group represented by formula (P-1) is —OCO—CH═CH₂ or —OCO—C(CH₃)═CH₂. A wavy line in formulas (P-1) to (P-5) shows a site to be bonded.

In formulas (P-1) to (P-5), M¹, M² and M³ are independently hydrogen, fluorine, alkyl having 1 to 5 carbons, or alkyl having 1 to 5 carbons in which at least one of hydrogen is replaced by fluorine or chlorine. Preferred M¹, M² or M³ is hydrogen or methyl in order to increase reactivity. Further preferred M¹ is hydrogen or methyl and further preferred M² or M³ is hydrogen.

Sp¹, Sp² and Sp³ are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one of —CH₂— may be replaced by —O—, —COO—, —OCO— or —OCOO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH— or —C≡C—, and in the groups, at least one of hydrogen may be replaced by fluorine or chlorine. Preferred Sp¹, Sp² or Sp³ is a single bond, —CH₂—CH₂—, —CH₂O—, —OCH₂—, —OCO—, —OCO—, —CO—CH═CH— or —CH═CH—OC—. Further preferred Sp¹, Sp² or Sp³ is a single bond.

Ring K and ring M are independently cyclohexyl, cyclohexenyl, phenyl, 1-naphthyl, 2-naphthyl, tetrahydropyran-2-yl, 1,3-dioxane-2-yl, pyrimidine-2-yl or pyridine-2-yl, and in the rings, at least one of hydrogen may be replaced by fluorine, chlorine, alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine. Preferred ring K or ring M is phenyl. Ring L is 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, naphthalene-1,2-diyl, naphthalene-1,3-diyl, naphthalene-1,4-diyl, naphthalene-1,5-diyl, naphthalene-1,6-diyl, naphthalene-1,7-diyl, naphthalene-1,8-diyl, naphthalene-2,3-diyl, naphthalene-2,6-diyl, naphthalene-2,7-diyl, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, pyrimidine-2,5-diyl or pyridine-2,5-diyl, and in the rings, at least one of hydrogen may be replaced by fluorine, chlorine, alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine. Preferred ring L is 1,4-phenylene or 2-fluoro-1,4-phenylene.

Z⁶ and Z⁷ are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one of —CH₂— may be replaced by —O—, —CO—, —COO— or —OCO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH—, —C(CH₃)═CH—, —CH═C(CH₃)— or —C(CH₃)═C(CH₃)—, and in the groups, at least one of hydrogen may be replaced by fluorine or chlorine. Preferred Z⁶ or Z⁷ is a single bond, —CH₂—CH₂—, —CH₂O—, —OCH₂—, —COO—, or —OCO—. Further preferred Z⁶ or Z⁷ is a single bond.

Then, g is 0, 1 or 2. Preferred g is 0 or 1. Then, h, j and k are independently 0, 1, 2, 3 or 4, and a sum of h, j and k is 1 or more. Preferred h, j or k is 1 or 2.

Fifth, the preferred component compound will be shown. Preferred compound (1) includes compounds (1-1) to (1-3) described in item 2.

Preferred compound (3) includes compounds (3-1) to (3-12) described in item 5. In the compounds, at least one of the third components preferably includes compound (3-2), (3-4), (3-5) or (3-6). At least two of the third components preferably include a combination of compounds (3-2) and (3-4), or a combination of compounds (3-2) and (3-6).

Preferred compound (4) includes compounds (4-1) to (4-19) described in item 8. In the compounds, at least one of the fourth components preferably includes compound (4-1), (4-2), (4-3), (4-4), (4-6), (4-7), (4-8) or (4-10). At least two of the fourth components preferably include a combination of compounds (4-1) and (4-6), a combination of compounds (4-1) and (4-10), a combination of compounds (4-3) and (4-6), a combination of compounds (4-3) and (4-10), a combination of compounds (4-4) and (4-6), or a combination of compounds (4-4) and (4-10).

Preferred compound (5) includes compounds (5-1) to (5-27) described in item 12. In the compounds, at least one of the additive components preferably includes compound (5-1), (5-2), (5-24), (5-25), (5-26) or (5-27). At least two of the additive components preferably include a combination of compounds (5-1) and (5-2), a combination of compounds (5-1) and (5-18), a combination of compounds (5-2) and (5-24), a combination of compounds (5-2) and (5-25), a combination of compounds (5-2) and (5-26), a combination of compounds (5-25) and (5-26), or a combination of compounds (5-18) and (5-24).

Sixth, the additive that may be added to the composition will be described. Such an additive includes the optically active compound, the antioxidant, the ultraviolet light absorber, the dye, the antifoaming agent, the polymerizable compound, the polymerization initiator, the polymerization inhibitor and so forth. The optically active compound is added to the composition for the purpose of inducing a helical structure in the liquid crystal molecules to give a twist angle. Examples of such a compound include compounds (6-1) to (6-5). A preferred ratio of the optically active compound is approximately 5% by weight or less. A further preferred ratio is in the range of approximately 0.01% by weight to approximately 2% by weight.

The antioxidant is added to the composition for the purpose of preventing a decrease in the specific resistance caused by heating in air, or maintaining a large voltage holding ratio at room temperature and also at a temperature close to the maximum temperature even after the device has been used for a long period of time. Preferred examples of the antioxidant include compound (7) where n is an integer from 1 to 9, or the like.

In compound (7), preferred n is 1, 3, 5, 7 or 9. Further preferred n is 7. Compound (7) where n is 7 is effective in maintaining a large voltage holding ratio at room temperature and also at a temperature close to the maximum temperature even after the device has been used for a long period of time because such compound (7) has a small volatility. A preferred ratio of the antioxidant is approximately 50 ppm or more for achieving the effect thereof, and approximately 600 ppm or less for avoiding a decrease in the maximum temperature or avoiding an increase in the minimum temperature. A further preferred ratio is in the range of approximately 100 ppm to approximately 300 ppm.

Preferred examples of the ultraviolet light absorber include a benzophenone derivative, a benzoate derivative and a triazole derivative. A light stabilizer such as an amine having steric hindrance is also preferred. A preferred ratio of the ultraviolet light absorber or the stabilizer is approximately 50 ppm or more for achieving the effect thereof, and approximately 10,000 ppm or less for avoiding a decrease in the maximum temperature or avoiding an increase in the minimum temperature. A further preferred ratio is in the range of approximately 100 ppm to approximately 10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is added to the composition to be adapted for a device having a guest host (GH) mode. A preferred ratio of the dye is in the range of approximately 0.01% by weight to approximately 10% by weight. The antifoaming agent such as dimethyl silicone oil or methyl phenyl silicone oil is added to the composition for preventing foam formation. A preferred ratio of the antifoaming agent is approximately 1 ppm or more for achieving the effect thereof, and approximately 1,000 ppm or less for preventing the poor display. A further preferred ratio is in the range of approximately 1 ppm to approximately 500 ppm.

The polymerizable compound is used to be adapted for a polymer sustained alignment (PSA) mode device. Compound (5) is suitable for the purpose. Any other polymerizable compound that is different from compound (5) may be added to the composition together with compound (5). In place of compound (5), any other polymerizable compound that is different from compound (5) may be added to the composition. Preferred examples of the polymerizable compounds include acrylate, methacrylate, a vinyl compound, a vinyloxy compound, propenyl ether, an epoxy compound (oxirane and oxetane) and a vinyl ketone compound. Further preferred examples include an acrylate derivative or a methacrylate derivative. A preferred ratio of compound (5) is approximately 10% by weight or more based on the total weight of the polymerizable compound. A further preferred ratio is approximately 50% by weight or more. A particularly preferred ratio is approximately 80% by weight or more. A most preferred ratio is approximately 100% by weight.

The polymerizable compound such as compound (5) is polymerized by irradiation with ultraviolet light, and may be polymerized in the presence of a suitable initiator such as a photopolymerization initiator. Suitable conditions for polymerization, suitable types of the initiator and suitable amounts thereof are known to those skilled in the art and are described in literature. For example, Irgacure 651 (registered trademark; BASF), Irgacure 184 (registered trademark; BASF) or Darocur 1173 (registered trademark; BASF), each being a photoinitiator, is suitable for radical polymerization. A preferred ratio of the photopolymerization initiator is in the range of approximately 0.1% by weight to approximately 5% by weight based on the total weight of the polymerizable compound. A further preferred ratio is in the range of approximately 1% by weight to approximately 3% by weight based thereon.

When the polymerizable compound such as compound (5) is stored, the polymerization inhibitor may be added thereto in order to prevent polymerization. The polymerizable compound is ordinarily added to the composition without removing the polymerization inhibitor. Examples of the polymerization inhibitor include hydroquinone, a hydroquinone derivative such as methylhydroquinone, 4-tert-butylcatechol, 4-methoxyphenol and phenothiazine.

Seventh, the methods for synthesizing the component compounds will be described. The compounds can be prepared according to known methods. Examples of synthetic methods will be described. Compound (1-2) is prepared by the method described in JP 2003-517494 A. Compound (2) is prepared by the method described in JP S59-70624 A. Compound (3-1) is prepared by the method described in JP S56-68636 A. Compound (4-1) is prepared by the method described in JP H2-503441 A. Compound (5-18) is prepared by the method described in JP H7-101900 A. The antioxidant is commercially available. A compound represented by formula (7) where n is 1 is available from Sigma-Aldrich Corporation. Compound (7) where n is 7 and so forth are prepared according to the method described in U.S. Pat. No. 3,660,505 B.

Any compounds whose synthetic methods are not described above can be prepared according to the methods described in books such as Organic Syntheses (John Wiley & Sons, Inc.), Organic Reactions (John Wiley & Sons, Inc.), Comprehensive Organic Synthesis (Pergamon Press) and New Experimental Chemistry Course (Shin Jikken Kagaku Koza in Japanese) (Maruzen Co., Ltd.). The composition is prepared according to a publicly known method using the thus obtained compounds. For example, the component compounds are mixed and dissolved in each other by heating.

Last, the application of the composition will be described. Most of the compositions have a minimum temperature of approximately −10° C. or lower, a maximum temperature of approximately 70° C. or higher, and an optical anisotropy in the range of approximately 0.07 to approximately 0.20. The composition having an optical anisotropy in the range of approximately 0.08 to approximately 0.25 may be prepared by controlling the ratio of the component compounds or by mixing any other liquid crystal compound. Further the composition having an optical anisotropy in the range of approximately 0.10 to approximately 0.30 may be prepared by the method. The device including the composition has a large voltage holding ratio. The composition is suitable for use in the AM device. The composition is particularly suitable for use in a transmissive AM device. The composition can be used as the composition having the nematic phase and as the optically active composition by adding the optically active compound.

The composition can be used for the AM device. The composition can also be used for a PM device. The composition can be used for an AM device and a PM device both having a mode such as PC, TN, STN, ECB, OCB, IPS, FFS, VA or FPA. Use for the AM device having the TN mode, the OCB mode, the IPS mode or the FFS mode is particularly preferred. In the AM device having the IPS mode or the FFS mode, alignment of liquid crystal molecules when no voltage is applied may be parallel or vertical to a glass substrate. The devices may be of a reflective type, a transmissive type or a transflective type. Use for the transmissive device is preferred. The composition can also be used for an amorphous silicon-TFT device or a polycrystal silicon-TFT device. The composition can also be used for a nematic curvilinear aligned phase (NCAP) device prepared by microencapsulating the composition, or for a polymer dispersed (PD) device in which a three-dimensional network-polymer is formed in the composition.

It will be apparent to those skilled in the art that various modifications and variations can be made in the invention and specific examples provided herein without departing from the spirit or scope of the invention. Thus, it is intended that the invention covers the modifications and variations of this invention that come within the scope of any claims and their equivalents.

The following examples are for illustrative purposes only and are not intended, nor should they be interpreted to, limit the scope of the invention.

EXAMPLES

The invention will be described in more detail by way of Examples. The invention is not limited by the Examples. The invention includes a mixture of a composition in Example 1 and a composition in Example 2. The invention also includes a mixture in which at least two compositions in Examples were mixed. A compound prepared was identified by a method such as an NMR analysis. Characteristics of the compound, the composition and a device were measured by methods described below.

NMR analysis: For measurement, DRX-500 made by Bruker BioSpin Corporation was used. In ¹H-NMR measurement, a sample was dissolved in a deuterated solvent such as CDCl₃, and measurement was carried out under conditions of room temperature, 500 MHz and 16 times of accumulation. Tetramethylsilane was used as an internal standard. In ¹⁹F-NMR measurement, measurement was carried out under conditions of 24 times of accumulation using CFCl₃ as an internal standard. In the explanation of a nuclear magnetic resonance spectrum, s, d, t, q, quip, sex and m stand for a singlet, a doublet, a triplet, a quartet, a quintet, a sextet and a multiplet, respectively, and br means being broad.

Gas chromatographic analysis: GC-14B Gas Chromatograph made by Shimadzu Corporation was used for measurement. A carrier gas was helium (2 mL per minute). A sample injector and a detector (FID) were set to 280° C. and 300° C., respectively. A capillary column DB-1 (length 30 m, bore 0.32 mm, film thickness 0.25 μm; dimethylpolysiloxane as a stationary phase, non-polar) made by Agilent Technologies, Inc. was used for separation of component compounds. After a column was kept at 200° C. for 2 minutes, the column was heated to 280° C. at a rate of 5° C. per minute. A sample was prepared in an acetone solution (0.1% by weight), and then 1 microliter of the solution was injected into the sample injector. A recorder was C-R5A Chromatopac made by Shimadzu Corporation or the equivalent thereof. The resulting gas chromatogram showed a peak retention time and a peak area corresponding to each of the component compounds.

As a solvent for diluting the sample, chloroform, hexane or the like may also be used. The following capillary columns may also be used for separating the component compounds: HP-1 (length 30 m, bore 0.32 mm, film thickness 0.25 μm) made by Agilent Technologies, Inc., Rtx-1 (length 30 m, bore 0.32 mm, film thickness 0.25 μm) made by Restek Corporation and BP-1 (length 30 m, bore 0.32 mm, film thickness 0.25 μm) made by SGE International Pty. Ltd. A capillary column CBP1-M50-025 (length 50 m, bore 0.25 mm, film thickness 0.25 μm) made by Shimadzu Corporation may also be used for the purpose of avoiding an overlap of peaks of the compounds.

A ratio of liquid crystal compounds contained in the composition may be calculated by the method as described below. A mixture of the liquid crystal compounds was detected by gas chromatograph (FID). A ratio of the peak areas in the gas chromatogram corresponds to a ratio (weight ratio) of the liquid crystal compounds. When the capillary column described above was used, a correction coefficient of each of the liquid crystal compounds may be regarded as 1 (one). Accordingly, a ratio (% by weight) of the liquid crystal compounds can be calculated from the ratio of the peak areas.

Sample for measurement: When characteristics of the composition and the device were measured, the composition was used as was. When characteristics of the compound were measured, a sample for measurement was prepared by mixing the compound (15% by weight) with a base liquid crystal (85% by weight). Values of characteristics of the compound were calculated using values obtained by measurement, according to an extrapolation method: (extrapolated value)={(measured value of a sample for measurement)−0.85×(measured value of a base liquid crystal)}/0.15. When a smectic phase (or crystals) precipitated at the ratio thereof at 25° C., a ratio of the compound to the base liquid crystal was changed step by step in the order of (10% by weight: 90% by weight), (5% by weight: 95% by weight) and (1% by weight: 99% by weight). Values of maximum temperature, optical anisotropy, viscosity and dielectric anisotropy with regard to the compound were determined according to the extrapolation method.

The base liquid crystal described below was used. A ratio of the component compound was expressed in terms of weight percent (% by weight).

Measuring method: Characteristics were measured by methods described below. Most of the methods are applied as described in the Standard of Japan Electronics and Information Technology Industries Association (hereinafter, abbreviated as JEITA) discussed and established as the Standard of JEITA (JEITA ED-2521B), or as modified thereon. No thin film transistor (TFT) was attached to a TN device used for measurement.

(1) Maximum temperature of a nematic phase (NI; ° C.): A sample was placed on a hot plate in a melting point measuring apparatus equipped with a polarizing microscope and was heated at a rate of 1° C. per minute. Temperature when part of the sample began to change from a nematic phase to an isotropic liquid was measured. A higher limit of a temperature range of the nematic phase may be occasionally abbreviated as “maximum temperature.”

(2) Minimum temperature of a nematic phase (T_(a); ° C.): Samples each having a nematic phase were put in glass vials and kept in freezers at temperatures of 0° C., −10° C., −20° C., −30° C. and −40° C. for 10 days, and then liquid crystal phases were observed. For example, when the sample maintained the nematic phase at −20° C. and changed to crystals or a smectic phase at −30° C., T_(c) was expressed as T_(c)<−20° C. A lower limit of the temperature range of the nematic phase may be occasionally abbreviated as “minimum temperature.”

(3) Viscosity (bulk viscosity; q; measured at 20° C.; mPa·s): A cone-plate (E type) rotational viscometer made by Tokyo Keiki Inc. was used for measurement.

(4) Viscosity (rotational viscosity; γ1; measured at 25° C.; mPa·s): Measurement was carried out according to the method described in M. Imai et al., Molecular Crystals and Liquid Crystals, Vol. 259, p. 37 (1995). A sample was put in a VA device in which a distance (cell gap) between two glass substrates was 20 micrometers. Voltage was applied stepwise to the device in the range of 39 V to 50 V at an increment of 1 V. After 0.2 second with no voltage application, voltage was applied repeatedly under conditions of only one rectangular wave (rectangular pulse; 0.2 second) and no application (2 seconds). A peak current and a peak time of a transient current generated by the applied voltage were measured. A value of rotational viscosity was obtained from the measured values according to calculating equation (8) on page 40 of the paper presented by M. Imai et al. Dielectric anisotropy required for the calculation was measured by the method described in section (6).

(5) Optical anisotropy (refractive index anisotropy; Δn; measured at 25° C.): Measurement was carried out by an Abbe refractometer having a polarizing plate mounted on an ocular, using light at a wavelength of 589 nanometers. A surface of a main prism was rubbed in one direction, and then a sample was added dropwise onto the main prism. A refractive index (n∥) was measured when the direction of polarized light was parallel to the direction of rubbing. A refractive index (n⊥) was measured when the direction of polarized light was perpendicular to the direction of rubbing. A value of optical anisotropy was calculated from an equation: Δn=n∥−n⊥.

(6) Dielectric anisotropy (As; measured at 25° C.): A value of dielectric anisotropy was calculated from an equation: Δ∈=∈∥−∈⊥. A dielectric constant (∈∥ and ∈⊥) was measured as described below.

(1) Measurement of dielectric constant (∈∥): An ethanol (20 mL) solution of octadecyltriethoxysilane (0.16 mL) was applied to a well-cleaned glass substrate. After rotating the glass substrate with a spinner, the glass substrate was heated at 150° C. for 1 hour. A sample was put in a VA device in which a distance (cell gap) between two glass substrates was 4 micrometers, and the device was sealed with an ultraviolet-curable adhesive. Sine waves (0.5V, 1 kHz) were applied to the device, and after 2 seconds, a dielectric constant (∈∥) in the major axis direction of liquid crystal molecules was measured.

(2) Measurement of dielectric constant (∈⊥): A polyimide solution was applied to a well-cleaned glass substrate. After calcining the glass substrate, rubbing treatment was applied to the alignment film obtained. A sample was put in a TN device in which a distance (cell gap) between two glass substrates was 9 micrometers and a twist angle was 80 degrees. Sine waves (0.5 V, 1 kHz) were applied to the device, and after 2 seconds, a dielectric constant (∈⊥) in the minor axis direction of the liquid crystal molecules was measured.

(7) Threshold voltage (Vth; measured at 25° C.; V): An LCD-5100 luminance meter made by Otsuka Electronics Co., Ltd. was used for measurement. A light source was a halogen lamp. A sample was put in a normally black mode VA device in which a distance (cell gap) between two glass substrates was 4 micrometers and a rubbing direction was anti-parallel, and the device was sealed with an ultraviolet-curable adhesive. A voltage (60 Hz, rectangular waves) to be applied to the device was stepwise increased from 0 V to 20 V at an increment of 0.02 V. On the occasion, the device was irradiated with light from a direction perpendicular to the device, and an amount of light transmitted through the device was measured. A voltage-transmittance curve was prepared, in which a maximum amount of light corresponds to 100% transmittance and a minimum amount of light corresponds to 0% transmittance. A threshold voltage is expressed in terms of a voltage at 10% transmittance.

(8) Voltage holding ratio (VHR-1; measured at 25° C.; %): A TN device used for measurement had a polyimide alignment film and a distance (cell gap) between two glass substrates was 5 micrometers. A sample was put in the device, and then the device was sealed with an ultraviolet-curable adhesive. A pulse voltage (60 microseconds at 5 V) was applied to the TN device and the device was charged. A decaying voltage was measured for 16.7 milliseconds with a high-speed voltmeter, and area A between a voltage curve and a horizontal axis in a unit cycle was determined. Area B was an area without decay. A voltage holding ratio is expressed in terms of a percentage of area A to area B.

(9) Voltage holding ratio (VHR-2; measured at 80° C.; %): A voltage holding ratio was measured in procedures identical with the procedures described above except that the voltage holding ratio was measured at 80° C. in place of 25° C. The values obtained were expressed by VHR-2.

(10) Voltage holding ratio (VHR-3; measured at 25° C.; %): Stability to ultraviolet light was evaluated by measuring a voltage holding ratio after a device was irradiated with ultraviolet light. A TN device used for measurement had a polyimide alignment film, and a cell gap was 5 micrometers. A sample was injected into the device, and then the device was irradiated with light for 20 minutes. Alight source was an ultra high-pressure mercury lamp USH-500D (made by Ushio, Inc.), and a distance between the device and the light source was 20 centimeters. In measuring VHR-3, a decaying voltage was measured for 16.7 milliseconds. A composition having a large VHR-3 has a large stability to ultraviolet light. A value of VHR-3 is preferably 90% or more, and further preferably, 95% or more.

(11) Voltage holding ratio (VHR-4; measured at 25° C.; %): A TN device into which a sample was injected was heated in a constant-temperature bath at 80° C. for 500 hours, and then stability to heat was evaluated by measuring a voltage holding ratio. In measuring VHR-4, a decaying voltage was measured for 16.7 milliseconds. A composition having a large VHR-4 has a large stability to heat.

(12) Response time (i; measured at 25° C.; ms): An LCD-5100 luminance meter made by Otsuka Electronics Co., Ltd. was used for measurement. A light source was a halogen lamp. A low-pass filter was set at 5 kHz. A sample was put in a normally black mode VA device in which a distance (cell gap) between two glass substrates was 4 micrometers and a rubbing direction was anti-parallel. Then, the device was sealed using an ultraviolet-curable adhesive. Rectangular waves (60 Hz, 10 V, 0.5 second) were applied to the device. On the occasion, the device was irradiated with light from a direction perpendicular to the device, and an amount of light transmitted through the device was measured. The maximum amount of light corresponds to 100% transmittance, and the minimum amount of light corresponds to 0% transmittance. A response time was expressed in terms of time required for a change from 90% transmittance to 10% transmittance (fall time; millisecond).

(13) Specific resistance (p; measured at 25° C.; Ωcm): Into a vessel equipped with electrodes, 1.0 milliliter of sample was injected. A DC voltage (10 V) was applied to the vessel, and a DC current after 10 seconds was measured. A specific resistance was calculated from the following equation: (specific resistance)={(voltage)×(electric capacity of a vessel)}/{(direct current)×(dielectric constant of vacuum)}.

The compounds in Examples were described using symbols according to definitions in Table 3 below. In Table 3, a configuration of 1,4-cyclohexylene is trans. A parenthesized number next to a symbolized compound corresponds to the number of the compound. A symbol (-) means any other liquid crystal compound. A ratio (percentage) of the liquid crystal compound is expressed in terms of weight percent (% by weight) based on the weight of the liquid crystal composition. Values of the characteristics of the composition were summarized in the last part.

TABLE 3 Method for Description of Compounds using Symbols R—(A₁)—Z₁— . . . —Z_(n)—(A_(n))—R′ 1) Left-terminal Group R— Symbol FC_(n)H_(2n)— Fn— C_(n)H_(2n+1)— n— C_(n)H_(2n+1)O— nO— C_(m)H_(2m+1)OC_(n)H_(2n)— mOn— CH₂═CH— V— C_(n)H_(2n+1)—CH═CH— nV— CH₂═CH—C_(n)H_(2n)— Vn— C_(m)H_(2m+1)—CH═CH—C_(n)H_(2n)— mVn— CF₂═CH— VFF— CF₂═CH—C_(n)H_(2n)— VFFn— C_(m)H_(2m+1)CF₂C_(n)H_(2n)— m(CF2)n— CH₂═CHCOO— AC— CH₂═C(CH₃)COO— MAC— 2) Right-terminal Group —F Symbol —C_(n)H_(2n+1) —n —OC_(n)H_(2n+1) —On —CH═CH₂ —V —CH═CH—C_(n)H_(2n+1) —Vn —C_(n)H_(2n)—CH═CH₂ —nV —C_(m)H_(2m)—CH═CH—C_(n)H_(2n+1) —mVn —CH═CF₂ —VFF —OCOCH═CH₂ —AC —OCOC(CH₃)═CH₂ —MAC 3) Bonding Group —Zn— Symbol —C_(n)H_(2n) n —COO— E —CH═CH— V —CH═CHO— VO —OCH═CH— OV —CH₂O— 1O —OCH₂— O1 4) Ring Structure —An— Symbol

H

B

B(F)

B(2F)

B(2F,5F)

B(2F,3F)

B(2F,3Cl)

dh

Dh

ch

Cro(7F,8F) 5) Examples of Description Example 1. 3-B(2F)B(2F,3F)—O2

Example 2. 5-DhB(2F,3F)—O2

Example 3. 3-BB-1

Example 4. AC—BB—AC

Comparative Example 1

Example 15 was selected from the compositions disclosed in JP 2003-327965 A. The basis thereof is that the composition contains compound (1-1), (3-5), (4-1) and (4-10). The components and characteristics of the composition were as described below.

3-HH-V1 (—) 8% 5-HH-V (—) 18% 2-BB(2F)B(2F,3F)-O2 (1-1) 10% 3-BB(2F)B(2F,3F)-O2 (1-1) 4% 3-HB(2F,3F)-O4 (4-1) 16% 5-HB(2F,3F)-O2 (4-1) 8% 5-HB(2F,3F)-O4 (4-1) 8% 3-HBB-2 (3-5) 8% 2-HBB(2F,3F)-O2 (4-10) 10% 3-HBB(2F,3F)-O2 (4-10) 10%

NI=72.0° C.; Δn=0.116; γ1=133.0 mPa·s.

Example 1

For comparison, a composition similar to the composition in Comparative Example 1 was prepared. Compound 5-HH-V in Comparative Example 1 was replaced by compound (2). Viscosity of the composition in Comparative Example 1 was 133.0 mPa·s and viscosity of the composition in Example 1 was 117.5 mPa·s, and therefore the composition in Example 1 was found to have a smaller viscosity.

3-BB(2F)B(2F,3F)-O2 (1-1) 7% 5-BB(2F)B(2F,3F)-O2 (1-1) 7% 2-HH-3 (2) 18% 3-HBB-2 (3-5) 8% 3-HB(2F,3F)-O4 (4-1) 16% 5-HB(2F,3F)-O2 (4-1) 8% 5-HB(2F,3F)-O4 (4-1) 8% 2-HBB(2F,3F)-O2 (4-10) 10% 3-HBB(2F,3F)-O2 (4-10) 10% 3-HH-V1 (—) 8%

NI=67.8° C.; η=22.7 mPa·s; Δn=0.114; Δ∈=−3.8; Vth=1.97 V; γ1=114.2 mPa·s.

Example 2

5-BB(2F)B(2F,3F)-O2 (1-1) 3% 5-BB(F)B(2F,3F)-O2 (1-2) 3% 2-HH-2 (2) 13% V2-BB-1 (3-2) 8% 1V2-BB-1 (3-2) 6% 3-HHB-1 (3-4) 4% 3-HHB-3 (3-4) 4% 3-HHEBH-5 (3-9) 3% 5-HBB(F)B-3 (3-12) 3% 3-H1OB(2F,3F)-O2 (4-3) 7% 3-BB(2F,3F)-O2 (4-4) 9% 5-B(2F,3F)B(2F,3F)-O2 (4-5) 3% 2-HHB(2F,3F)-O2 (4-6) 4% V2-HHB(2F,3F)-O2 (4-6) 6% 2-HH1OB(2F,3F)-O2 (4-8) 4% 3-HH1OB(2F,3F)-O2 (4-8) 8% 3-HEB(2F,3F)B(2F,3F)-O2 (4-11) 3% 5-HHB(2F,3Cl)-O2 (4-12) 3% 3-HH1OCro(7F,8F)-5 (4-15) 3% 3-dhBB(2F,3F)-O2 (4-17) 3%

NI=88.2° C.; η=24.9 mPa·s; Δn=0.124; Δ∈=−3.2; Vth=1.99 V; γ1=123.0 mPa·s.

Example 3

3-BB(2F)B(2F,3F)-O2 (1-1) 3% 3-BB(F)B(2F,3F)-O2 (1-2) 3% 5-B(F)BB(2F,3F)-O2 (1-3) 3% 2-HH-3 (2) 17% 3-HB-O2 (3-1) 5% 3-HHEH-3 (3-3) 4% 3-HHEH-5 (3-3) 4% V-HHB-1 (3-4) 5% 3-H2B(2F,3F)-O2 (4-2) 4% 5-H2B(2F,3F)-O2 (4-2) 4% 3-BB(2F,3F)-O2 (4-4) 7% 5-BB(2F,3F)-O2 (4-4) 4% 2-HH1OB(2F,3F)-O2 (4-8) 10% 3-HH1OB(2F,3F)-O2 (4-8) 14% 2-chB(2F,3F)-O2 (4-18) 5% 3-HchB(2F,3F)-O2 (4-19) 8%

NI=80.1° C.; η=24.3 mPa·s; Δn=0.107; Δ∈=−4.2; Vth=1.79 V; γ1=121.6 mPa·s.

Example 4

3-BB(2F)B(2F,3F)-O2 (1-1) 3% 5-BB(2F)B(2F,3F)-O2 (1-1) 3% 3-BB(F)B(2F,3F)-O2 (1-2) 3% 5-BB(F)B(2F,3F)-O2 (1-2) 2% 2-HH-3 (2) 10% 1-BB-3 (3-2) 5% 1V2-BB-1 (3-2) 5% VFF2-HHB-1 (3-4) 4% 3-HBB-2 (3-5) 4% 5-B(F)BB-2 (3-7) 3% V-HB(2F,3F)-O2 (4-1) 12% 3-BB(2F,3F)-O2 (4-4) 8% 5-BB(2F,3F)-O2 (4-4) 5% 3-HHB(2F,3F)-O2 (4-6) 6% V-HHB(2F,3F)-O1 (4-6) 3% V-HHB(2F,3F)-O4 (4-6) 5% 3-HH1OB(2F,3F)-O2 (4-8) 3% 2-HBB(2F,3F)-O3 (4-10) 7% V-HBB(2F,3F)-O2 (4-10) 3% 3-HDhB(2F,3F)-O2 (4-16) 3% 1O1-HBBH-5 (—) 3%

NI=77.7° C.; η=25.3 mPa·s; Δn=0.143; Δ∈=−3.1; Vth=2.01 V; γ1=127.1 mPa·s.

Example 5

3-BB(2F)B(2F,3F)-O2 (1-1) 3% 5-BB(2F)B(2F,3F)-O2 (1-1) 2% 3-BB(F)B(2F,3F)-O2 (1-2) 2% 5-B(F)BB(2F,3F)-O2 (1-3) 3% 2-HH-3 (2) 18% 1-BB-5 (3-2) 5% 2-BB(F)B-3 (3-6) 4% 3-HB(F)HH-2 (3-8) 4% V-H1OB(2F,3F)-O2 (4-3) 9% 3-BB(2F,3F)-O2 (4-4) 9% 3-HH2B(2F,3F)-O2 (4-7) 7% 5-HH2B(2F,3F)-O2 (4-7) 7% 3-HH1OB(2F,3F)-O2 (4-8) 9% 2-BB(2F,3F)B-4 (4-9) 5% 2-HBB(2F,3F)-O2 (4-10) 3% 3-HBB(2F,3F)-O2 (4-10) 3% 3-H1OCro(7F,8F)-5 (4-14) 3% 2-HH-5 (—) 4%

NI=76.4° C.; η=24.9 mPa·s; Δn=0.125; Δ∈=−3.6; Vth=1.88 V; γ1=125.0 mPa·s.

Example 6

3-BB(2F)B(2F,3F)-O2 (1-1) 2% 5-BB(2F)B(2F,3F)-O2 (1-1) 3% 3-B(F)BB(2F,3F)-O2 (1-3) 3% 2-HH-3 (2) 20% 1-BB-3 (3-2) 7% 3-HHB-O1 (3-4) 3% 3-HHB-1 (3-4) 3% 3-HHB-3 (3-4) 3% 3-BB(2F,3F)-O2 (4-4) 12% 5-BB(2F,3F)-O2 (4-4) 8% 2-HH1OB(2F,3F)-O2 (4-8) 10% 3-HH1OB(2F,3F)-O2 (4-8) 20% 3-HH-4 (—) 6%

NI=71.8° C.; η=20.9 mPa·s; Δn=0.111; Δ∈=−3.7; Vth=1.87 V; γ1=104.9 mPa·s.

Example 7

3-BB(2F)B(2F,3F)-O2 (1-1) 3% 5-BB(2F)B(2F,3F)-O2 (1-1) 2% 3-BB(F)B(2F,3F)-O2 (1-2) 3% 2-HH-3 (2) 15% 1-BB-3 (3-2) 7% V-HHB-1 (3-4) 7% V2-HHB-1 (3-4) 5% 3-BB(2F,3F)-O2 (4-4) 8% 5-BB(2F,3F)-O2 (4-4) 5% 2-HH1OB(2F,3F)-O2 (4-8) 10% 3-HH1OB(2F,3F)-O2 (4-8) 10% V-HH1OB(2F,3F)-O2 (4-8) 9% 2-BB(2F,3F)B-3 (4-9) 9% 2-BB(2F,3F)B-4 (4-9) 7%

NI=81.5° C.; η=24.4 mPa·s; Δn=0.140; Δ∈=−3.5; Vth=1.92 V; γ1=122.4 mPa·s.

Example 8

3-BB(2F)B(2F,3F)-O2 (1-1) 2% 5-BB(2F)B(2F,3F)-O2 (1-1) 3% 5-BB(F)B(2F,3F)-O2 (1-2) 3% 2-HH-3 (2) 16% 3-HHB-O1 (3-4) 4% 3-HHB-1 (3-4) 4% 3-HHB-3 (3-4) 4% 5-HBBH-3 (3-10) 3% 5-HB(F)BH-3 (3-11) 4% 3-HB(2F,3F)-O2 (4-1) 8% 3-BB(2F,3F)-O2 (4-4) 11% V2-BB(2F,3F)-O2 (4-4) 5% 2-HH1OB(2F,3F)-O2 (4-8) 9% 3-HH1OB(2F,3F)-O2 (4-8) 15% V-chB(2F,3F)-O2 (4-18) 6% 3-HH-VFF (—) 3%

NI=81.5° C.; η=24.7 mPa·s; Δn=0.112; Δ∈=−3.6; Vth=1.90 V; γ1=123.4 mPa·s.

Example 9

3-BB(2F)B(2F,3F)-O2 (1-1) 3% 3-BB(F)B(2F,3F)-O2 (1-2) 4% 2-HH-3 (2) 19% 1-BB-5 (3-2) 4% VFF-HHB-1 (3-4) 3% V-HHB-1 (3-4) 4% V2-HHB-1 (3-4) 3% 2-BB(F)B-2V (3-6) 3% 3-BB(2F,3F)-O2 (4-4) 8% 5-BB(2F,3F)-O2 (4-4) 7% V-HHB(2F,3F)-O2 (4-6) 6% 3-HH2B(2F,3F)-O2 (4-7) 7% 5-HH2B(2F,3F)-O2 (4-7) 8% 3-HH1OB(2F,3F)-O2 (4-8) 14% 3-HEB(2F,3F)B(2F,3F)-O2 (4-11) 3% 3-HHB(2F,3Cl)-O2 (4-12) 4%

NI=91.9° C.; η=23.7 mPa·s; Δn=0.120; Δ∈=−3.4; Vth=1.96 V; γ1=118.4 mPa·s.

Example 10

3-BB(F)B(2F,3F)-O2 (1-2) 3% 5-B(F)BB(2F,3F)-O2 (1-3) 3% 2-HH-3 (2) 25% V2-BB-1 (3-2) 5% V-HBB-3 (3-5) 3% 2-BB(F)B-5 (3-6) 5% 5-B(F)BB-3 (3-7) 3% 3-BB(2F,3F)-O2 (4-4) 10% 5-BB(2F,3F)-O2 (4-4) 7% 2-HH1OB(2F,3F)-O2 (4-8) 4% 3-HH1OB(2F,3F)-O2 (4-8) 7% V-HH1OB(2F,3F)-O2 (4-8) 13% 3-HBB(2F,3Cl)-O2 (4-13) 4% 5-HBB(2F,3Cl)-O2 (4-13) 4% 3-HDhB(2F,3F)-O2 (4-16) 4%

NI=73.6° C.; η=24.7 mPa·s; Δn=0.124; Δ∈=−3.4; Vth=1.97 V; γ1=123.9 mPa·s.

Example 11

5-BB(2F)B(2F,3F)-O2 (1-1) 3% 3-BB(F)B(2F,3F)-O2 (1-2) 3% 2-HH-3 (2) 22% 5-HB-O2 (3-1) 4% 7-HB-1 (3-1) 5% 1-BB(F)B-2V (3-6) 4% 3-BB(F)B-2V (3-6) 4% 3-HHEBH-3 (3-9) 3% 3-HHEBH-4 (3-9) 3% 3-BB(2F,3F)-O2 (4-4) 12% 2O-BB(2F,3F)-O2 (4-4) 5% 2-HH1OB(2F,3F)-O2 (4-8) 11% 3-HH1OB(2F,3F)-O2 (4-8) 18% V-HBB(2F,3F)-O2 (4-10) 3%

NI=87.6° C.; η=23.2 mPa·s; Δn=0.120; Δ∈=−3.4; Vth=1.95 V; γ1=116.6 mPa·s.

Example 12

5-BB(2F)B(2F,3F)-O2 (1-1) 3% 3-BB(F)B(2F,3F)-O2 (1-2) 3% 5-BB(F)B(2F,3F)-O2 (1-2) 3% 2-HH-3 (2) 21% V2-BB-1 (3-2) 4% V-HHB-1 (3-4) 8% V2-HHB-1 (3-4) 8% V-HBB-2 (3-5) 5% V-HB(2F,3F)-O2 (4-1) 4% 3-HB(2F,3F)-O2 (4-1) 5% 3-H1OB(2F,3F)-O2 (4-3) 8% 3-BB(2F,3F)-O2 (4-4) 6% 5-B(2F,3F)B(2F,3F)-O2 (4-5) 3% 3-HH1OB(2F,3F)-O2 (4-8) 19%

NI=71.7° C.; η=18.5 mPa·s; Δn=0.108; Δ∈=−3.2; Vth=1.98 V; γ1=92.8 mPa·s.

The composition in Example 1 had a smaller viscosity (yl) in comparison with the composition in Comparative Example 1. The compositions in Examples 2 to 12 had a viscosity in the range of 92.8 mPa·s to 127.1 mPa·s. Accordingly, the liquid crystal composition according to the invention is concluded to have further excellent characteristics.

Although the invention has been described and illustrated with a certain degree of particularity, it is understood that the disclosure has been made only by way of example, and that numerous changes in the conditions and order of steps can be resorted to by those skilled in the art without departing from the spirit and scope of the invention.

INDUSTRIAL APPLICABILITY

A liquid crystal composition of the invention satisfies at least one of characteristics such as a high maximum temperature, a low minimum temperature, a small viscosity, a suitable optical anisotropy, a large negative dielectric anisotropy, a large specific resistance, a high stability to ultraviolet light and a high stability to heat, or has a suitable balance regarding at least two of the characteristics. A liquid crystal display device including such a composition has characteristics such as a short response time, a large voltage holding ratio, a low threshold voltage, a large contrast ratio and a long service life, and thus can be used for a liquid crystal projector, a liquid crystal television and so forth. 

What is claimed is:
 1. A liquid crystal composition that has a negative dielectric anisotropy, and contains at least one compound selected from the group of compounds represented by formula (1) as a first component, and a compound represented by formula (2) as a second component:

wherein, in formula (1), R¹ and R² are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxy having 2 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine; Z¹ and Z² are independently a single bond, ethylene, carbonyloxy or methyleneoxy; and X¹, X², X³ and X⁴ are independently hydrogen, fluorine or chlorine, wherein, at least one of X¹, X², X³ and X⁴ is fluorine or chlorine.
 2. The liquid crystal composition according to claim 1, containing at least one compound selected from the group of compounds represented by formulas (1-1) to (1-3) as the first component:

wherein, in formulas (1-1) to (1-3), R¹ and R² are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxy having 2 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine.
 3. The liquid crystal composition according to claim 1, wherein a ratio of the first component is in the range of 5% by weight to 30% by weight, and a ratio of the second component is in the range of 5% by weight to 40% by weight based on the weight of the liquid crystal composition.
 4. The liquid crystal composition according to claim 1, containing at least one compound selected from the group of compounds represented by formula (3) as a third component:

wherein, in formula (3), R³ and R⁴ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine, or alkenyl having 2 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine; ring A and ring B are independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene or 2,5-difluoro-1,4-phenylene; Z³ is a single bond, ethylene or carbonyloxy; n is 1, 2 or 3; wherein, when n is 1, ring B is 1,4-phenylene.
 5. The liquid crystal composition according to claim 4, containing at least one compound selected from the group of compounds represented by formulas (3-1) to (3-12) as the third component:

wherein, in formulas (3-1) to (3-12), R³ and R⁴ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine, or alkenyl having 2 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine.
 6. The liquid crystal composition according to claim 4, wherein a ratio of the third component is in the range of 5% by weight to 50% by weight based on the weight of the liquid crystal composition.
 7. The liquid crystal composition according to claim 1, containing at least one compound selected from the group of compounds represented by formula (4) as a fourth component:

wherein, in formula (4), R⁵ and R⁶ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxy having 2 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine; ring C and ring E are independently 1,4-cyclohexylene, 1,4-cyclohexenylene, tetrahydropyran-2,5-diyl, 1,4-phenylene, or 1,4-phenylene in which at least one of hydrogen is replaced by fluorine or chlorine; ring D is 2,3-difluoro-1,4-phenylene, 2-chloro-3-fluoro-1,4-phenylene, 2,3-difluoro-5-methyl-1,4-phenylene, 3,4,5-trifluoronaphthalene-2,6-diyl or 7,8-difluorochroman-2,6-diyl; Z⁴ and Z⁵ are independently a single bond, ethylene, carbonyloxy or methyleneoxy; p is 1, 2 or 3; q is 0 or 1; a sum of p and q is 3 or less; wherein, when p is 2 and q is 0, at least one of ring C is 1,4-cyclohexylene, 1,4-cyclohexenylene or tetrahydropyran-2,5-diyl.
 8. The liquid crystal composition according to claim 7, containing at least one compound selected from the group of compounds represented by formulas (4-1) to (4-19) as the fourth component:

wherein, in formulas (4-1) to (4-19), R⁵ and R⁶ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxy having 2 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine.
 9. The liquid crystal composition according to claim 7, wherein a ratio of the fourth component is in the range of 10% by weight to 80% by weight based on the weight of the liquid crystal composition.
 10. The liquid crystal composition according to claim 4, containing at least one compound selected from the group of compounds represented by formula (4) as a fourth component:

wherein, in formula (4), R⁵ and R⁶ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxy having 2 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine; ring C and ring E are independently 1,4-cyclohexylene, 1,4-cyclohexenylene, tetrahydropyran-2,5-diyl, 1,4-phenylene, or 1,4-phenylene in which at least one of hydrogen is replaced by fluorine or chlorine; ring D is 2,3-difluoro-1,4-phenylene, 2-chloro-3-fluoro-1,4-phenylene, 2,3-difluoro-5-methyl-1,4-phenylene, 3,4,5-trifluoronaphthalene-2,6-diyl or 7,8-difluorochroman-2,6-diyl; Z⁴ and Z⁵ are independently a single bond, ethylene, carbonyloxy or methyleneoxy; p is 1, 2 or 3; q is 0 or 1; a sum of p and q is 3 or less; wherein, when p is 2 and q is 0, at least one of ring C is 1,4-cyclohexylene, 1,4-cyclohexenylene or tetrahydropyran-2,5-diyl.
 11. The liquid crystal composition according to claim 1, containing at least one polymerizable compound selected from the group of compounds represented by formula (5) as an additive component:

wherein, in formula (5), ring K and ring M are independently cyclohexyl, cyclohexenyl, phenyl, 1-naphthyl, 2-naphthyl, tetrahydropyran-2-yl, 1,3-dioxane-2-yl, pyrimidine-2-yl or pyridine-2-yl, and in the rings, at least one of hydrogen may be replaced by fluorine, chlorine, alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine; ring L is 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, naphthalene-1,2-diyl, naphthalene-1,3-diyl, naphthalene-1,4-diyl, naphthalene-1,5-diyl, naphthalene-1,6-diyl, naphthalene-1,7-diyl, naphthalene-1,8-diyl, naphthalene-2,3-diyl, naphthalene-2,6-diyl, naphthalene-2,7-diyl, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, pyrimidine-2,5-diyl or pyridine-2,5-diyl, and in the rings, at least one of hydrogen may be replaced by fluorine, chlorine, alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine; Z⁶ and Z⁷ are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one of —CH₂— may be replaced by —O—, —CO—, —COO— or —OCO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH—, —C(CH₃)═CH—, —CH═C(CH₃)— or —C(CH₃)═C(CH₃)—, and in the groups, at least one of hydrogen may be replaced by fluorine or chlorine; P¹, P² and P³ are independently a polymerizable group; Sp¹, Sp² and Sp³ are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one of —CH₂— may be replaced by —O—, —COO—, —OCO— or —OCOO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH— or —C≡C—, and in the groups, at least one of hydrogen may be replaced by fluorine or chlorine; g is 0, 1 or 2; h, j and k are independently 0, 1, 2, 3 or 4; and a sum of h, j and k is 1 or more.
 12. The liquid crystal composition according to claim 11, wherein, in formula (5), P¹, P² and P³ are independently a polymerizable group selected from the group of groups represented by formulas (P-1) to (P-5):

wherein, in formulas (P-1) to (P-5), M¹, M² and M³ are independently hydrogen, fluorine, alkyl having 1 to 5 carbons, or alkyl having 1 to 5 carbons in which at least one of hydrogen is replaced by fluorine or chlorine.
 13. The liquid crystal composition according to claim 11, containing at least one polymerizable compound selected from the group of compounds represented by formulas (5-1) to (5-27) as the additive component:

wherein, in formulas (5-1) to (5-27), P⁴, P⁵ and P⁶ are independently a polymerizable group selected from the group of groups represented by formulas (P-1) to (P-3):

wherein, in formulas (P-1) to (P-3), M¹, M² and M³ are independently hydrogen, fluorine, alkyl having 1 to 5 carbons, or alkyl having 1 to 5 carbons in which at least one of hydrogen is replaced by fluorine or chlorine; in formulas (5-1) to (5-27), Sp¹, Sp² and Sp³ are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one of —CH₂— may be replaced by —O—, —COO—, —OCO— or —OCOO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH— or —C≡C—, and in the groups, at least one of hydrogen may be replaced by fluorine or chlorine.
 14. The liquid crystal composition according to claim 11, wherein a ratio of addition of the additive component is in the range of 0.03% by weight to 10% by weight based on the weight of the liquid crystal composition.
 15. The liquid crystal composition according to claim 4, containing at least one polymerizable compound selected from the group of compounds represented by formula (5) as an additive component:

wherein, in formula (5), ring K and ring M are independently cyclohexyl, cyclohexenyl, phenyl, 1-naphthyl, 2-naphthyl, tetrahydropyran-2-yl, 1,3-dioxane-2-yl, pyrimidine-2-yl or pyridine-2-yl, and in the rings, at least one of hydrogen may be replaced by fluorine, chlorine, alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine; ring L is 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, naphthalene-1,2-diyl, naphthalene-1,3-diyl, naphthalene-1,4-diyl, naphthalene-1,5-diyl, naphthalene-1,6-diyl, naphthalene-1,7-diyl, naphthalene-1,8-diyl, naphthalene-2,3-diyl, naphthalene-2,6-diyl, naphthalene-2,7-diyl, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, pyrimidine-2,5-diyl or pyridine-2,5-diyl, and in the rings, at least one of hydrogen may be replaced by fluorine, chlorine, alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine; Z⁶ and Z⁷ are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one of —CH₂— may be replaced by —O—, —CO—, —COO— or —OCO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH—, —C(CH₃)═CH—, —CH═C(CH₃)— or —C(CH₃)═C(CH₃)—, and in the groups, at least one of hydrogen may be replaced by fluorine or chlorine; P¹, P² and P³ are independently a polymerizable group; Sp¹, Sp² and Sp³ are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one of —CH₂— may be replaced by —O—, —COO—, —OCO— or —OCOO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH— or —C≡C—, and in the groups, at least one of hydrogen may be replaced by fluorine or chlorine; g is 0, 1 or 2; h, j and k are independently 0, 1, 2, 3 or 4; and a sum of h, j and k is 1 or more.
 16. The liquid crystal composition according to claim 7, containing at least one polymerizable compound selected from the group of compounds represented by formula (5) as an additive component:

wherein, in formula (5), ring K and ring M are independently cyclohexyl, cyclohexenyl, phenyl, 1-naphthyl, 2-naphthyl, tetrahydropyran-2-yl, 1,3-dioxane-2-yl, pyrimidine-2-yl or pyridine-2-yl, and in the rings, at least one of hydrogen may be replaced by fluorine, chlorine, alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine; ring L is 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, naphthalene-1,2-diyl, naphthalene-1,3-diyl, naphthalene-1,4-diyl, naphthalene-1,5-diyl, naphthalene-1,6-diyl, naphthalene-1,7-diyl, naphthalene-1,8-diyl, naphthalene-2,3-diyl, naphthalene-2,6-diyl, naphthalene-2,7-diyl, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, pyrimidine-2,5-diyl or pyridine-2,5-diyl, and in the rings, at least one of hydrogen may be replaced by fluorine, chlorine, alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine; Z⁶ and Z⁷ are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one of —CH₂— may be replaced by —O—, —CO—, —COO— or —OCO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH—, —C(CH₃)═CH—, —CH═C(CH₃)— or —C(CH₃)═C(CH₃)—, and in the groups, at least one of hydrogen may be replaced by fluorine or chlorine; P¹, P² and P³ are independently a polymerizable group; Sp¹, Sp² and Sp³ are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one of —CH₂— may be replaced by —O—, —COO—, —OCO— or —OCOO—, at least one of —CH₂—CH₂— may be replaced by —CH═CH— or —C≡C—, and in the groups, at least one of hydrogen may be replaced by fluorine or chlorine; g is 0, 1 or 2; h, j and k are independently 0, 1, 2, 3 or 4; and a sum of h, j and k is 1 or more.
 17. A liquid crystal display device, including the liquid crystal composition according to claim
 1. 18. The liquid crystal display device according to claim 17, wherein an operating mode in the liquid crystal display device is an IPS mode, a VA mode, an FFS mode or an FPA mode, and a driving mode in the liquid crystal display device is an active matrix mode.
 19. A polymer sustained alignment mode liquid crystal display device, wherein the liquid crystal display device includes the liquid crystal composition according to claim 11, or the polymerizable compound in the liquid crystal composition is polymerized.
 20. A liquid crystal composition that has a negative dielectric anisotropy, and contains at least one compound represented by formula (1-3) as a first component, and a compound represented by formula (2) as a second component:

wherein, in formula (1-3), R¹ and R² are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxy having 2 to 12 carbons, or alkyl having 1 to 12 carbons in which at least one of hydrogen is replaced by fluorine or chlorine. 